1. Field of the Invention
The present invention relates to a high frequency cable TV apparatus, and in particular to an RF directional coupler circuit having improved high frequency (1.0 GHz or above 1.0 GHz) impedance matching with signal taps of high frequency cable TV apparatus.
2. Description of Prior Art
Currently the signals of cable TV are tapped and transmitted by the cable TV apparatus, so that the signals of cable TV are transmitted to different buildings or communities. Accordingly, users in the buildings or communities can watch cable TV programs.
Currently the frequencies of the signals of cable TV are higher and higher (1.0 GHz), so that when the signals of cable TV are transmitted, the signals of cable TV are fading, and the image quality of TV in client sites is worse. The main reason is that the high frequency impedance is not matching.
A conventional cable TV apparatus 10 (as shown in the FIG. 1) includes a cover body 101 having a space 102. A printed circuit board 20 is arranged on a plurality of protruding pillars 103 in the space 102. A long distance 30 is formed between the printed circuit board 20 and the bottom of the space 102. When the high frequency signals are transmitted through an RF directional coupler circuit 201 on the printed circuit board 20, there are a lot of signal reflections because of the distance 30, so that the impedance is not matching, the signals of cable TV have serious fading, and the image quality of TV in clients is worse.